So far, I have only had one issue with the combat styles. I made a new character after transferring one from the live server. I chose the knight story and guardian as my primary combat style then did the mission to get my second style and chose sage. I was able to swap between the two classes for a while and then all of a sudden, I could only use my sage combat style and couldn't switch back to guardian. But when I could switch styles, the abilities stayed where I had put them.